Optical systems for reading optical code symbols such as bar code, matrix code and two-dimensional symbologies are well known. Some known imaging optical code reading systems are capable of reading a variety of different codes from various angles and distances. Generally, imagers and laser beam scanning systems electro-optically transform optical code into electrical signals which are decoded into alpha-numerical characters or other data. These data are in digital form and are used as input to a data processing system in, for example, a point of sale (POS) environment for looking up a price for the article.
Laser scanner modules and imaging optical code reading modules typically have a field of view centered about an optical axis or line of sight. Ideally the scanner module or imager module reads a bar code in the working range located on an optical plane substantially perpendicular to the line of sight. However, most scanner modules and imager modules can effectively read codes on many other planes and surfaces at a variety of different angles and orientations within the field of view.
Early scanning systems were constructed with single aiming axes or fields of view, and required precise positioning of the code symbol with respect to the scanning head.
Scanners with two planar scanning windows oriented at an angle to one another have become popular for both supermarkets and mass merchandisers. Such scanners increase the checkout throughput, which is important in environments where large numbers of articles products are scanned. With one planar scan module, an operator has to ensure that the bar code symbol is oriented in the single field of view and at a working distance that enables a beam to read the symbol. Systems with two window scanners reduce the amount of manipulation that the operator has to perform in properly positioning the article for scanning. In a two window scanner system, the operator only has to ensure that the bar code symbol is read throughout at least one of the scan windows. Such systems may include a horizontal scanning window and a generally vertical scanning window from which laser lines for scanning bar code symbols originate. Typically, an operator is situated on the side of the scanner that is opposite the vertical scanning window.
Some such scanners can perform adequately in reading bar code symbols on any of four sides of an article positioned in the system. These sides are, from an operator's point of view, the side of the article facing down, the side of the article positioned away from the operator (facing the vertical window), the leading side of the article (the side pointing in the article's direction of travel) and the trailing side of the article. One known scanner, the Spectra Physics Magellan Scanner, also attempts to read symbols positioned on the side opposite to a vertical window (i.e., the side of the article facing the operator), but it is only successful when the article is positioned at least a predetermined distance from the operator or if the symbol is very close to the bottom of the article. The laser lines that read symbols on this side of the scanner are emitted though the horizontal scanning window on which the article is located. These lines project upwards and away from the operator at about 45 degrees and require a distance of travel before they can reach a certain height on the side of the article. An NCR scanner is also capable of reading symbols on the top of the scanned article.
In conventional systems, an operator visually locates the symbol as he or she moves the article towards the scanner. The system can read the code only if it is located in such a position so that it passes through the field of view of one of the scan heads in one of the windows. If the symbol is not located in such a position, the operator must re-orient the product and pass it over the scanner. In practice, if the operator cannot visually locate the symbol, he assumes that it may be on the side of the article that is facing downward or on the side of the article facing the vertical scanning window. The operator has to decide if he wants to risk moving it through the scanning system without locating the symbol, hoping that the system will find the symbol. The operator will not be certain that his hand is not covering the symbol. If the operator decides to make an attempt at scanning without locating the symbol and the scan attempt fails to locate or read a symbol, the operator will have to move the article back and try again, this time locating the symbol visually to assure success. This is time consuming, and therefore, is an inefficient process. Many operators will avoid such a scenario by visually locating the symbol and repositioning the article, if necessary, before moving the article through the scanning system. This usually assures a reading on the first attempt but the process requires a certain amount of time which reduces the efficiency of the scanning operation. Moreover, in order to visually locate the symbol, the article must be turned so the symbol is pointed towards the operator. The vertical window of conventional two window scanners, however, is positioned to read symbols on the side of the article facing away from an operator. Thus, operators must rotate the product towards themselves to locate the symbol, and then re-orient the package towards either the horizontal or vertical window.
It has been proposed to configure optical code reading systems with more than two aiming axes or fields of view in order to achieve more reliable or complete scanning. Examples of systems utilizing a plurality of scan modules oriented with their respective lines of sight aiming in different directions, so as to nominally scan two or more optimal planes within a scanning volume are illustrated in U.S. Pat. No. 5,495,097, assigned to Symbol Technologies, Inc. Two systems disclosed in the aforementioned patent are illustrated in FIGS. 1 and 2. Elements 10 in the Figures are scan modules or heads. The system of FIG. 1 includes a conveyor 12 which moves code bearing articles past the scanning heads. The system is an example of what is generally referred to as a "tunnel scanner". The system of FIG. 2 employs a counter 14 on which code bearing objects are supported or moved. This system is referred to as an "inverted tunnel scanner".
While such systems theoretically provide improved optical code reading capabilities over conventional systems, there is a need to develop code reading systems with multiple fields of view which can more accurately, reliably and inexpensively read optical codes which are essentially randomly oriented with respect to the system and the operator.
Accordingly, it is an object of the present invention to provide code reading systems which are ergometrically acceptable and capable of reading codes from multiple fields of view intersecting a position or path of the coded article. This would eliminate the time consuming and repetitive motion of re-orienting the article towards one of the scan heads or imagers provided by today's systems.
It is another object of the present invention to provide such a system which is simply and inexpensively fabricated.
It is another object of the present invention to provide a code reading system which minimizes or reduces obstructions to the views and movements of the operator.
It is another object of the present invention to provide a code reading system which incorporates hand held readers, information displays and data inputs for operator and customer, while minimizing obstructions to their views.
It is another object of the present invention to provide tunnel and inverted tunnel scanner which requires a minimum amount of hardware and provides high performance from a small number of scan modules and/or imager modules.
Many conventional scanning systems are used in conjunction with a point of sale installation or check out counter. In many cases a single or double window slot scanner or a single hand held scanner or imager module is used in the code reading process. Some audible and visual indicators are provided at the installation such as the familiar beep and price displays. Weighing stations are sometimes also provided. In general, these code reading systems are often add-on items and not well integrated with other structures and functions at the installation.
It is a further object of the present invention to provide integrated weighing systems for use with optical code readers.
It is another object of the present invention to provide more accessible and useful visible and audible information concerning the code reading process to the operator and/or customer.
It is yet another object to integrate code reading devices with multiple fields of view into a point of sale system having greater capabilities for data acquisition and data display.
These and other objects and features will be apparent from this written disclosure and accompanying drawings.